Distance-adjustable stress detection device and method for monitoring state of coupling liquid

Abstract

The invention discloses a distance-adjustable stress detection device and method for monitoring the state of coupling liquid, and belongs to the field of ultrasonic nondestructive testing. The device comprises a first wedge block, a second wedge block, a linkage module, a liquid supplementing pipeline and a liquid pump. A linkage module capable of changing the horizontal distance between the first wedge block and the second wedge block is installed between the first wedge block and the second wedge block. The bottom surfaces of the first wedge block and the second wedge block are sunken inwards to form a coupling agent groove; the liquid pump is communicated with the liquid supplementing inlet through a liquid supplementing pipeline, so that a coupling agent can enter the coupling agent groove through the liquid supplementing outlet to fill the lower surface of the wedge block and the surface of the detected workpiece; a transmitting probe and a receiving probe are respectively arranged at the tops of the first wedge block and the second wedge block in a mirror symmetry manner; and the receiving probe is connected with an upper computer through a data acquisition module to feed back and adjust the liquid pump. The problem that a traditional wedge block cannot optimize the sound wave propagation path in dynamic detection is solved, matching of the sound wave path and the actual detection condition is achieved, and the detection precision and stability are further improved.

Description

Technical Field

[0001] The invention belongs to the field of ultrasonic nondestructive testing, and in particular relates to a stress detection device and method capable of adjusting distance and monitoring coupling liquid state. Background Art

[0002] In the dynamic detection process of the plane stress field on the material surface, ultrasonic detection technology (especially the detection method based on LCR waves) has been widely used in aerospace, shipbuilding, composite material processing and other fields due to its high precision, non-destructiveness and real-time performance. In the dynamic detection of the plane stress field of the material, the adjustment of the wedge spacing and the maintenance of the coupling state play a key role in the detection accuracy and reliability of the results. At present, the wedge spacing is mainly determined by fixed wedges. At the same time, in the process of ultrasonic residual stress detection, the coupling liquid between the wedge and the material surface is the key medium for ultrasonic signal transmission. The coupling agent is a water-soluble polymer colloid that can exclude the air between the probe and the workpiece to ensure that the sound wave can be effectively transmitted to the material to be tested.

[0003] At present, the spacing of the most commonly used fixed wedges is fixed at the design stage and cannot be flexibly adjusted according to different detection requirements. This method has a simple structure, but lacks adaptability and cannot meet the requirements of different materials and different stress field detection scenarios. At the same time, ultrasonic coupling devices generally use a method in which the coupling agent is directly applied to the bottom surface of the wedge fixed by the probe to make the wedge contact the surface of the workpiece to be measured. This method has significant defects: the distribution uniformity of the coupling agent is difficult to control, and local gaps or bubbles are prone to occur, resulting in unstable ultrasonic signal transmission. The coating amount cannot be accurately grasped. Too much will cause the coupling agent to be lost, and too little will not form effective acoustic coupling, affecting the detection quality. In addition, the commonly used low-viscosity coupling agent is prone to relative sliding between the wedge and the workpiece surface during the contact process, resulting in a deviation in the detection position, affecting the accuracy and repeatability of the results. At the same time, due to the unstable coupling state, the amplitude and acoustic time difference of the ultrasonic signal observed during the detection process are prone to fluctuations, and the waveform cannot remain stable, causing interference in the subsequent data acquisition and analysis process, greatly affecting the reliability and accuracy of the measurement. In addition, the monitoring and maintenance of the coupling status mainly rely on manual observation and experience judgment, and operators usually make manual judgments by observing the filling status of the coupling fluid. This method is highly subjective and cannot achieve real-time monitoring and feedback adjustment. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a stress detection device and method with adjustable distance and monitoring coupling fluid state. The device solves the problem that the wedge distance cannot be adjusted and solves the problem that the coupling state affects the test results.

[0005] The specific technical solutions adopted by the present invention are as follows:

[0006] In a first aspect, the present invention provides a stress detection device with adjustable distance and capable of monitoring the state of a coupling fluid, comprising a first wedge block, a second wedge block, a linkage module, a fluid replenishment pipeline, and a liquid pump;

[0007] A linkage module capable of changing the horizontal distance between the first wedge block and the second wedge block is installed between the first wedge block and the second wedge block; the first wedge block and the second wedge block both have a hollow inner cavity, a liquid inlet is arranged on the top, a liquid inlet is arranged on the bottom, a coupling step is arranged on the outer side of the bottom, and the bottom surface is recessed inward to form a coupling agent groove; the liquid pump is connected to the liquid inlet through a liquid inlet pipeline, so that the coupling agent can enter the coupling agent groove through the liquid inlet outlet to fill the lower surface of the wedge block and the surface of the workpiece to be measured; the first wedge block and the second wedge block are respectively provided with a transmitting probe and a receiving probe on the top of the first wedge block and the second wedge block, and the receiving probe is connected to the host computer through the data acquisition module to feedback and adjust the liquid pump.

[0008] Preferably, the linkage module comprises a distance adjustment screw, a key, a lower gear, an internal gear and an upper gear shaft;

[0009] The rod body of the distance adjustment screw has threads at both ends with opposite thread directions, the shaft diameter of the middle part is enlarged to form shaft shoulders on both sides and is provided with keyways, and the threads at both ends of the distance adjustment screw are respectively matched and connected with the thread grooves on the inner sides of the first wedge block and the second wedge block; the lower gear is coaxially fixed to the distance adjustment screw by a key, so that the lower gear and the distance adjustment screw rotate synchronously; both ends of the upper gear shaft have gears with the same number of teeth, the gear at one end meshes with the lower gear, and the gear at the other end meshes with the internal gear; the shaft diameter of the middle part of the upper gear shaft is enlarged to form shaft shoulders on both sides; by rotating the internal gear, the upper gear shaft can drive the lower gear to rotate, and at the same time drive the distance adjustment screw to rotate to change the distance between the first wedge block and the second wedge block through a threaded connection.

[0010] Preferably, the shoulders on both sides of the distance adjusting screw are respectively connected to the inner ring sleeves of the first lower bearing and the second lower bearing; one end of the first lower bearing cooperates with the stepped hole of the first lower baffle plate, and the other end cooperates with the shoulder on one side of the distance adjusting screw; one end of the second lower bearing cooperates with the stepped hole of the second lower baffle plate, and the other end cooperates with the shoulder on the other side of the distance adjusting screw; the shoulders on both sides of the upper gear shaft are respectively connected to the inner ring sleeves of the first upper bearing and the second upper bearing; one end of the first upper bearing cooperates with the stepped hole of the first upper baffle plate, and the other end cooperates with the shoulder on one side of the upper gear shaft; one end of the second upper bearing cooperates with the second upper baffle plate, and the other end cooperates with the shoulder on the other side of the upper gear shaft.

[0011] Preferably, the first lower baffle plate and the first upper baffle plate together constitute a whole vertical first side plate, and the second lower baffle plate and the second upper baffle plate together constitute a whole vertical second side plate; the first side plate and the second side plate are respectively connected to the second cover plate in front and rear, and are respectively connected to the first cover plate above and below; the first side plate, the second side plate, the first cover plate and the second cover plate together constitute a shell structure.

[0012] Preferably, the first lower baffle plate, the first upper baffle plate, the second lower baffle plate and the second upper baffle plate are all provided with a plurality of threaded holes along the thickness direction, and the screws are connected to the first cover plate and the second cover plate through the threaded holes.

[0013] Preferably, the outer circumference of the internal gear is provided with a scale for reading the rotation angle.

[0014] Preferably, the first wedge block and the second wedge block have the same structure and are arranged in a mirror-symmetrical manner with the linkage module as the axis; the shape and size of the fluid replenishment inlet, fluid replenishment outlet, coupling step and coupling agent groove on the first wedge block and the second wedge block are the same, and the position is arranged in a mirror-symmetrical manner with the linkage module as the axis.

[0015] In a second aspect, the present invention provides a stress detection method using the stress detection device with adjustable distance and monitoring coupling liquid state as described in any one of the first aspects, which is specifically as follows:

[0016] The liquid pump injects coupling agent into the liquid replenishment inlet of the first wedge block and the second wedge block through the liquid replenishment pipeline, and the coupling agent gradually fills the entire coupling agent groove at the bottom of the first wedge block and the second wedge block through the liquid replenishment outlet;

[0017] By rotating the inner gear, the upper gear shaft drives the lower gear to rotate, and at the same time drives the distance adjustment screw to rotate, so that the first wedge block and the second wedge block move horizontally, and the relative distance between the first wedge block and the second wedge block is changed to adjust to a suitable stress monitoring distance; then the first wedge block and the second wedge block are connected to the workpiece to be measured to maintain reliable coupling;

[0018] The pulse transmitting device transmits a pulse signal to the transmitting probe, the receiving probe receives the signal sent by the transmitting probe and sends it to the data acquisition module after amplification by the amplifying device, and the data acquisition module realizes data interaction with the host computer through the serial communication port; the LCR wave signal is read from the host computer, and the coupling state is judged whether it is good by reading the amplitude of the LCR wave signal and the stability of the acoustic time difference obtained after the cross-correlation algorithm processing;

[0019] During the dynamic movement detection process, the first wedge and the second wedge can move smoothly on the surface of the workpiece to be tested, and the coupling liquid state is detected by the amplitude and acoustic time difference of the LCR wave signal. When the amplitude and acoustic time difference become unstable, the host computer sends a command to the liquid pump to replenish the coupling agent into the coupling agent groove through the liquid replenishment pipe.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) A device with adjustable wedge distance between the transceiver probes (i.e., the transmitting probe and the receiving probe) is designed. By rotating the scaled gear (i.e., the internal gear), the distance between the transceiver probes can be accurately adjusted. This solves the problem that a single measuring device in the prior art can only be used for one type of workpiece to be inspected, and the distance between the transceiver probes in the measuring device cannot be adjusted according to the parameters of the workpiece to be inspected. The wedge spacing can be flexibly adjusted to adapt to different workpiece sizes and inspection requirements. This solves the problem that traditional wedges cannot optimize the sound wave propagation path in dynamic inspection, realizes the matching of the sound wave path with the actual inspection conditions, and further improves the inspection accuracy and stability.

[0022] (2) A plane stress field monitoring device for automatically filling coupling liquid is designed. The coupling liquid groove is opened on the lower surface of the wedge to control the application position of the coupling liquid. The thickness of the coupling liquid is controlled by the thickness of the groove, so that the coupling liquid is applied evenly. At the same time, the problem of easy loss of coupling liquid and inability to add coupling liquid during the measurement process in the prior art is solved. The liquid pump and the coupling liquid groove are connected through a liquid replenishment pipe. The upper computer monitoring method is used to realize feedback adjustment and automatic replenishment of the coupling liquid during the measurement process, thereby avoiding measurement errors caused by uneven coupling state of the coupling liquid during the test. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a front view structural schematic diagram of the device of the present invention;

[0024] Figure 2 for Figure 1 A schematic diagram of the structure viewed from the top at 45°;

[0025] Figure 3 It is a schematic diagram of the meshing of the internal gears (including the lower gear, the upper gear and the internal gear) of the device of the present invention;

[0026] Figure 4 for Figure 3 Schematic diagram of the 45° structure;

[0027] Figure 5 for Figure 1 A schematic diagram of the structure viewed from the bottom at 45°;

[0028] Figure 6 It is the overall working schematic diagram of the device of the present invention;

[0029] The reference numerals in the figure are: first wedge block 101, second wedge block 102, distance adjusting screw 2, first lower baffle plate 3, first lower bearing 4, key 5, lower gear 6, second lower bearing 7, second lower baffle plate 8, internal gear 9, upper gear shaft 10, second upper baffle plate 11, second upper bearing 12, first upper bearing 13, first upper baffle plate 14, first cover plate 15, second cover plate 16, screw 17, transmitting probe 18, receiving probe 19, fluid infusion pipe 20, coupling step 21, coupling agent groove 22, liquid pump 23. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. The technical features in each embodiment of the present invention can be combined accordingly without conflicting with each other.

[0031] In the description of the present invention, it is to be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or indirectly connected, that is, there are intermediate elements. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0032] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for the purpose of distinguishing descriptions, and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features.

[0033] like Figure 1 and 2 As shown, a stress detection device for adjusting the distance and monitoring the coupling liquid state provided by the present invention mainly comprises a first wedge block 101, a second wedge block 102, a linkage module, a liquid replenishing pipeline 20 and a liquid pump 23. The stress detection device can adjust the horizontal distance between the first wedge block 101 and the second wedge block 102 through the linkage module, and can control the addition of the coupling liquid through the liquid replenishing pipeline 20 and the liquid pump 23.

[0034] The structure and connection method of each component will be described in detail below.

[0035] In the device of the present invention, a linkage module is installed between the first wedge block 101 and the second wedge block 102, and the horizontal distance between the first wedge block 101 and the second wedge block 102 can be changed through the linkage module.

[0036] As a preferred embodiment of the present invention, Figure 3 and 4 As shown, the linkage module mainly includes a distance adjustment screw 2, a key 5, a lower gear 6, an internal gear 9 and an upper gear shaft 10. The rod body of the distance adjustment screw 2 has threads at both ends and the thread directions are opposite. The shaft diameter of the middle part of the rod body is increased and a shoulder is formed with both sides and a keyway is opened. The threads at both ends of the distance adjustment screw 2 are respectively connected with the thread grooves on the inner side of the first wedge 101 and the second wedge 102. The lower gear 6 is matched with the keyway through the key 5 to achieve coaxial fixation with the distance adjustment screw 2, so that the lower gear 6 and the distance adjustment screw 2 can rotate synchronously. Both ends of the upper gear shaft 10 have gears with the same number of teeth. The gear at one end meshes with the lower gear 6, and the gear at the other end meshes with the internal gear 9. The shaft diameter of the middle part of the upper gear shaft 10 is increased, and a shoulder is formed with both sides. By rotating the internal gear 9, the upper gear shaft 10 can drive the lower gear 6 to rotate, and at the same time drive the distance adjustment screw 2 to rotate to change the distance between the first wedge 101 and the second wedge 102 through threaded connection.

[0037] In actual use, in order to make the linkage module form a whole, the following shell settings can also be performed:

[0038] like Figure 1 , 2 As shown in Figures 5 and 6, the two side shoulders of the distance adjustment screw 2 are respectively connected with the inner ring sleeves of the first lower bearing 4 and the second lower bearing 7. One end of the first lower bearing 4 is matched with the stepped hole of the first lower baffle 3, and the other end is matched with the shoulder of one side of the distance adjustment screw 2. One end of the second lower bearing 7 is matched with the stepped hole of the second lower baffle 8, and the other end is matched with the shoulder of the other side of the distance adjustment screw 2. In other words, the first lower bearing 4 and the second lower bearing 7 are respectively fixed in the stepped through holes of the first lower baffle 3 and the second lower baffle 8, and the bearing sleeve is on the distance adjustment screw 2, and one end thereof is supported by the shoulder of the screw to ensure axial fixation.

[0039] The shoulders on both sides of the upper gear shaft 10 are connected to the inner ring sleeves of the first upper bearing 13 and the second upper bearing 12 respectively. One end of the first upper bearing 13 cooperates with the stepped hole of the first upper baffle 14, and the other end cooperates with the shoulder on one side of the upper gear shaft 10. One end of the second upper bearing 12 cooperates with the second upper baffle 11, and the other end cooperates with the shoulder on the other side of the upper gear shaft 10. The first lower baffle 3 and the first upper baffle 14 together constitute a whole vertical first side plate, and the second lower baffle 8 and the second upper baffle 11 together constitute a whole vertical second side plate. The front and rear of the first side plate and the second side plate are respectively connected to the second cover plate 16 with the plate body vertical, and the top and bottom are respectively connected to the first cover plate 15 with the plate body horizontal. The first side plate, the second side plate, the first cover plate 15 and the second cover plate 16 together constitute a shell structure.

[0040] To facilitate installation, multiple threaded holes may be opened along the thickness direction on the first lower baffle plate 3, the first upper baffle plate 14, the second lower baffle plate 8 and the second upper baffle plate 11, and the screws 17 are connected to the first cover plate 15 and the second cover plate 16 through the threaded holes.

[0041] In order to facilitate adjustment, a scale for reading the rotation angle can be provided on the outer circumference of the inner gear 9, so that the rotation angle of the inner gear 9 can be accurately and clearly adjusted, thereby controlling the horizontal distance between the first wedge block 101 and the second wedge block 102. That is, the user can read the angle change through the scale provided on the outer surface of the inner gear 9, and accurately control the distance between the two wedge blocks, ensuring that different workpiece sizes and detection requirements are met.

[0042] Detection operation: After the adjustment is completed, the transmitting probe 18 and the receiving probe 19 are respectively installed in the fixed cavities of the two wedge blocks, and the stress field detection equipment is started to perform plane stress field measurement.

[0043] That is to say, the first lower baffle plate 3 and the second lower baffle plate 8 are rectangular parallelepiped, with threaded holes at the front and back, and stepped through holes at the left and right halves. The second cover plate 16 has eight through holes, which are fixed to the front and back threaded holes of the first lower baffle plate 3 and the second lower baffle plate 8 by screws 17. The stepped through holes of the first lower baffle plate 3 and the second lower baffle plate 8 block the first lower bearing 4 and the second lower bearing 7 respectively, and the first lower bearing 4 and the second lower bearing 7 are sleeved on the distance adjustment screw rod 2, and the other end is supported by the shoulder of the distance adjustment screw rod 2. The lower gear 6 is fixed by the key 5 and the keyway on the distance adjustment screw rod 2. The second upper baffle plate has a stepped through hole, and the first upper baffle plate has a stepped hole, which blocks the second upper bearing and the first upper bearing respectively. The second upper baffle plate and the first upper baffle plate have threaded holes at the front and back, and are fixed to the second cover plate 16 by screws 17. The second upper bearing and the first upper bearing are sleeved on the upper gear shaft, and the other end is supported by the shoulder. The gear in the middle of the upper gear shaft 10 meshes with the lower gear 6. The right part of the upper gear shaft 10 also has a gear that cooperates with the internal gear 9. The internal gear 9 has a scale on the surface, and the rotation angle can be read. The first upper baffle 3, the second lower baffle 8, the second upper baffle 11, and the first upper baffle 14 are all provided with threaded holes on the upper and lower sides, and are fixed with the through holes on the first cover plate 15 by screws 17 to form an overall frame structure.

[0044] In the device of the present invention, the first wedge block 101 and the second wedge block 102 both have a hollow inner cavity; Figure 2 As shown, the tops of the first wedge block 101 and the second wedge block 102 are both provided with a liquid replenishment inlet; Figure 5As shown, the bottom of the first wedge block 101 and the second wedge block 102 are both provided with a liquid replenishing outlet, and the outer side of the bottom is provided with a coupling step 21, and the bottom surface is inwardly recessed to form a coupling agent groove 22. In other words, the first wedge block 101 and the second wedge block 102 are respectively provided with a coupling step 21 at the lower surface test surface, and two coupling agent grooves 22 are respectively opened on the two coupling steps 21.

[0045] In actual use, the size and depth of the coupling agent groove 22 can be adjusted according to actual conditions.

[0046] As a preferred embodiment of the present invention, the first wedge 101 and the second wedge 102 have the same structure and are mirror-symmetrically arranged with the linkage module as the axis. The liquid inlet, liquid inlet outlet, coupling step 21 and coupling agent groove 22 on the first wedge 101 and the second wedge 102 are of the same shape and size, and are mirror-symmetrically arranged with the linkage module as the axis.

[0047] In the device of the present invention, Figure 6 As shown, the liquid pump 23 is connected to the liquid replenishment inlet through the liquid replenishment pipeline 20, so that the coupling agent can enter the coupling agent groove 22 through the liquid replenishment outlet to fill the lower surface of the wedge block and the surface of the workpiece to be measured. The top of the first wedge block 101 and the second wedge block 102 are respectively mirror-symmetrically provided with a transmitting probe 18 and a receiving probe 19, and the receiving probe 19 is connected to the host computer through a data acquisition module to feedback and adjust the liquid pump 23.

[0048] Using any of the above-mentioned stress detection devices with adjustable distance and capable of monitoring the state of coupling fluid, the present invention further provides a stress detection method, which is specifically as follows:

[0049] After the distance adjustment screw is fixed to the lower gear, the upper gear shaft, the internal gear, all the bearings, and the baffle cover, only the screws at both ends of the distance adjustment screw are exposed from the square device (i.e., the housing structure composed of the first side plate, the second side plate, the first cover plate 15, and the second cover plate 16). The screws at both ends of the distance adjustment screw are matched with the threaded holes on the inner sides of the first wedge block 101 and the second wedge block 102, and the first wedge block 101 and the second wedge block 102 are respectively installed with the linkage module.

[0050] The liquid pump 23 injects coupling agent into the fluid replenishment inlet of the first wedge block 101 and the second wedge block 102 through the fluid replenishment pipe 20, and the coupling agent gradually fills the entire coupling agent groove 22 at the bottom of the first wedge block 101 and the second wedge block 102 through the fluid replenishment outlet, that is, fills the gap between the lower surface of the wedge block and the surface of the workpiece to be measured.

[0051] By rotating the inner gear 9, the upper gear shaft 10 drives the lower gear 6 to rotate, and at the same time drives the distance adjustment screw 2 to rotate. The reverse threads on the left and right ends of the distance adjustment screw 2 cause the first wedge 101 and the second wedge 102 to move horizontally synchronously, changing the relative distance between the first wedge 101 and the second wedge 102, and realizing the precise adjustment of the distance between the wedges. The scale on the outer surface of the inner gear can accurately control the distance of the horizontal movement of the two wedges, thereby adjusting the distance between the two wedges to a suitable stress monitoring distance. Then, the first wedge 101 and the second wedge 102 are connected to the workpiece to maintain reliable coupling.

[0052] The pulse transmitting device transmits a pulse signal to the transmitting probe 18, and the receiving probe 19 receives the signal sent by the transmitting probe 18 and sends it to the data acquisition module after amplification by the amplifying device. The data acquisition module realizes data interaction with the host computer through the serial communication port. The LCR wave signal is read from the host computer, and the coupling state is judged whether it is good by reading the amplitude of the LCR wave signal and the stability of the acoustic time difference obtained after the cross-correlation algorithm processing.

[0053] During the dynamic movement detection process, the first wedge 101 and the second wedge 102 can move smoothly on the surface of the workpiece to be tested, and the coupling liquid state is detected by the amplitude and acoustic time difference of the LCR wave signal. After the amplitude and acoustic time difference become unstable, the host computer sends a command to the liquid pump 23 to replenish the coupling agent into the coupling agent groove 22 through the liquid replenishment pipeline 20 to maintain a good coupling state. During the dynamic movement of the wedge, the amplitude of the LCR wave signal and the stability of the acoustic time difference are continuously monitored, and the amount of coupling agent replenishment is automatically adjusted to ensure that the coupling state is always in the best state and avoid measurement errors caused by the loss of coupling agent.

[0054] The above-described embodiment is only a preferred solution of the present invention, but it is not intended to limit the present invention. A person skilled in the relevant technical field may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. A stress detection device with adjustable distance and monitoring coupling fluid state, characterized in that: It comprises a first wedge block (101), a second wedge block (102), a linkage module, a liquid infusion pipeline (20) and a liquid pump (23); A linkage module capable of changing the horizontal distance between the first wedge block (101) and the second wedge block (102) is installed between the first wedge block (101) and the second wedge block (102); the first wedge block (101) and the second wedge block (102) both have a hollow inner cavity, a liquid inlet is provided at the top, a liquid inlet is provided at the bottom, a coupling step (21) is provided at the outer side of the bottom, and the bottom surface is inwardly recessed to form a coupling agent groove (22); the liquid pump (23) is connected to the liquid inlet through a liquid inlet pipeline (20), so that the coupling agent can enter the coupling agent groove (22) through the liquid inlet to fill the lower surface of the wedge block and the surface of the workpiece to be measured; the tops of the first wedge block (101) and the second wedge block (102) are respectively arranged with a transmitting probe (18) and a receiving probe (19) in a mirror-symmetrical manner, and the receiving probe (19) is connected to a host computer through a data acquisition module to feedback and adjust the liquid pump (23).

2. A stress detection device with adjustable distance and monitoring coupling fluid state according to claim 1, characterized in that: The linkage module comprises a distance adjustment screw rod (2), a key (5), a lower gear (6), an internal gear (9) and an upper gear shaft (10); The rod body of the distance adjustment screw (2) has threads at both ends with the threads in opposite directions, the shaft diameter of the middle part is increased to form shaft shoulders with both sides and is provided with keyways, the threads at both ends of the distance adjustment screw (2) are respectively matched and connected with the thread grooves on the inner sides of the first wedge block (101) and the second wedge block (102); the lower gear (6) is coaxially fixed with the distance adjustment screw (2) through a key (5), so that the lower gear (6) and the distance adjustment screw (2) rotate synchronously; both ends of the upper gear shaft (10) have gears with the same number of teeth, the gear at one end meshes with the lower gear (6), and the gear at the other end meshes with the internal gear (9); the shaft diameter of the middle part of the upper gear shaft (10) is increased to form shaft shoulders with both sides; by rotating the internal gear (9), the upper gear shaft (10) can drive the lower gear (6) to rotate, and at the same time drive the distance adjustment screw (2) to rotate so as to change the distance between the first wedge block (101) and the second wedge block (102) through the threaded connection.

3. A stress detection device with adjustable distance and monitoring coupling fluid state according to claim 2, characterized in that: The shoulders on both sides of the distance adjustment screw (2) are respectively connected to the inner ring sleeves of the first lower bearing (4) and the second lower bearing (7); one end of the first lower bearing (4) cooperates with the stepped hole of the first lower baffle (3), and the other end cooperates with the shoulder on one side of the distance adjustment screw (2); one end of the second lower bearing (7) cooperates with the stepped hole of the second lower baffle (8), and the other end cooperates with the shoulder on the other side of the distance adjustment screw (2); the shoulders on both sides of the upper gear shaft (10) are respectively connected to the inner ring sleeves of the first upper bearing (13) and the second upper bearing (12); one end of the first upper bearing (13) cooperates with the stepped hole of the first upper baffle (14), and the other end cooperates with the shoulder on one side of the upper gear shaft (10); one end of the second upper bearing (12) cooperates with the second upper baffle (11), and the other end cooperates with the shoulder on the other side of the upper gear shaft (10).

4. A stress detection device with adjustable distance and monitoring coupling fluid state according to claim 3, characterized in that: The first lower baffle plate (3) and the first upper baffle plate (14) together constitute a whole vertical first side plate, and the second lower baffle plate (8) and the second upper baffle plate (11) together constitute a whole vertical second side plate; the first side plate and the second side plate are respectively connected to the second cover plate (16) at the front and rear, and are respectively connected to the first cover plate (15) at the top and bottom; the first side plate, the second side plate, the first cover plate (15) and the second cover plate (16) together constitute a shell structure.

5. A stress detection device with adjustable distance and capable of monitoring coupling fluid state according to claim 4, characterized in that: The first lower baffle plate (3), the first upper baffle plate (14), the second lower baffle plate (8) and the second upper baffle plate (11) are all provided with a plurality of threaded holes along the thickness direction, and the screws (17) are connected to the first cover plate (15) and the second cover plate (16) through the threaded holes.

6. A stress detection device with adjustable distance and capable of monitoring coupling fluid state according to claim 2, characterized in that: The outer circumference of the internal gear (9) is provided with a scale for reading the rotation angle.

7. A stress detection device with adjustable distance and capable of monitoring coupling fluid state according to claim 1, characterized in that: The first wedge block (101) and the second wedge block (102) have the same structure and are arranged in a mirror-symmetrical manner with the linkage module as the axis; the liquid replenishment inlet, liquid replenishment outlet, coupling step (21) and coupling agent groove (22) on the first wedge block (101) and the second wedge block (102) are of the same shape and size, and their positions are arranged in a mirror-symmetrical manner with the linkage module as the axis.

8. A stress detection method using the stress detection device with adjustable distance and monitoring coupling fluid state as claimed in any one of claims 2 to 7, characterized in that: The details are as follows: The liquid pump (23) injects coupling agent into the liquid replenishing inlets of the first wedge block (101) and the second wedge block (102) through the liquid replenishing pipeline (20), and the coupling agent gradually fills the entire coupling agent groove (22) at the bottom of the first wedge block (101) and the second wedge block (102) through the liquid replenishing outlet; By rotating the inner gear (9), the upper gear shaft (10) drives the lower gear (6) to rotate, and at the same time drives the distance adjustment screw (2) to rotate, so that the first wedge block (101) and the second wedge block (102) move horizontally, and the relative distance between the first wedge block (101) and the second wedge block (102) is changed to adjust to a suitable stress monitoring distance; then, the first wedge block (101) and the second wedge block (102) are connected to the workpiece to be measured to maintain reliable coupling; The pulse transmitting device transmits a pulse signal to the transmitting probe (18), the receiving probe (19) receives the signal sent by the transmitting probe (18) and sends it to the data acquisition module after amplification by the amplifying device, and the data acquisition module realizes data interaction with the host computer through the serial communication port; the LCR wave signal is read from the host computer, and the coupling state is judged whether it is good by reading the amplitude of the LCR wave signal and the stability of the acoustic time difference obtained after the cross-correlation algorithm is processed; During the dynamic movement detection process, the first wedge block (101) and the second wedge block (102) can move smoothly on the surface of the workpiece to be tested, and the state of the coupling liquid is detected by the amplitude and acoustic time difference of the LCR wave signal. After the amplitude and the acoustic time difference become unstable, the host computer sends a command to the liquid pump (23) to replenish the coupling agent into the coupling agent groove (22) through the liquid replenishing pipe (20).

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